infoschema: fix a goroutine leak in the test (#13782)
infoschema: fix a goroutine leak in the test (#13782)


kyle-wang/tidb,kyle-wang/tidb,Cofyc/tidb,ngaut/tidb,c4pt0r/tidb,coocood/tidb,EvilMcJerkface/tidb,ngaut/tidb,ngaut/tidb,pingcap/tidb,ming-relax/tidb,pingcap/tidb,pingcap/tidb,XuHuaiyu/tidb,kyle-wang/tidb,c4pt0r/tidb,c4pt0r/tidb,c4pt0r/tidb,Cofyc/tidb,pingcap/tidb,pingcap/tidb,ngaut/tidb,coocood/tidb,c4pt0r/tidb,kyle-wang/tidb,EvilMcJerkface/tidb,kyle-wang/tidb,c4pt0r/tidb,pingcap/tidb,XuHuaiyu/tidb,ngaut/tidb,ming-relax/tidb,ngaut/tidb,kyle-wang/tidb